docs: def table(tab):
      """Access IPTables transactionally in a uniform way.
  
      Ensures all access is done without autocommit and that only the outer
      most task commits, and also ensures we refresh once and commit once.
      """
      global open_tables
      if tab in open_tables:
          yield open_tables[tab]
      else:
          open_tables[tab] = iptc.Table(tab)
          open_tables[tab].refresh()
          open_tables[tab].autocommit = False
          yield open_tables[tab]
          open_tables[tab].commit()
          del open_tables[tab]